TORSIONAL RATTLE DIESEL/TCC NEW PARTS FOR VALVE BODY

Some 1982 and early production 1983 "K" trucks equipped with 6.2L diesel engines and 700-R4 transmissions may experience a noticeable torsional rattle when the converter clutch engages in second, third or fourth gear, under light to moderate throttle at speeds below 40 mph. This rattle condition which is torque converter clutch/drive train related, can be improved by increasing the TCC engagement speed to 40 mph.

This can be accomplished by replacing the converter clutch throttle valve, sleeve and spring in the valve body with P/N 8642970 (Figure 1). This service package will consist of the following:

Valve Converter Clutch Throttle Sleeve Converter Clutch Throttle Spring Converter Clutch Throttle Instruction Sheet

If an objectionable rattle still exists after installing the service package, additional noise dampening can be achieved by filling the propshaft with urethane foam per the following recommended procedure:

1. Obtain a urethane foam dispensing system, Insta-Foam Product's Model #9.5 Froth Pak Kit or equivalent, which is a small volume kit complete with all the required chemicals, dispensing equipment and instructions. A maximum of one (1) Froth pak Kit will be required to foam-fill a prop-shaft from a long wheel base vehicle such as a Suburban or Pick-up.

2. Remove propshaft from vehicle.

3. After pivoting U-joints to allow a drill bit access to face of yoke, drill a 21/64" hole in face of each end yoke. Use caution not to damage U-joint seals (see illustration).

4. Wrap and tape U-joints with cloth.

5. Following directions and observing caution notes on kit, fill propshaft with spray foam from the top hole while maintaining propshaft in vertical position.

When foam begins to ooze out of application hole past the nozzle, enough foam has been dispensed. To pre- vent spewing of foam on operator, part, etc., do not remove nozzle from yoke until foaming activity sub-sides and set-up begins.

6. Allow foam to set, then remove U-joint cloth cover.

7. Drill out each end yoke hole and plug with silicone RTV rubber adhesive sealant (hi-heat resistance).

8. Reinstall propshaft assembly in vehicle.

Labor Operation Number: T0084

Labor Time: .9 hours

Add to foam fill propshaft .7

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.